Elastomeric compositions containing olefin-acrylic ester copolymer

ABSTRACT

ELASTOMERIC COMPOSITIONS COMPRISIG 1 PART BY WEIGHT OF AT LEAST ONE CURABLE ELASTOMER AND 0.01 TO 100 PARTS BY WEIGHT OF AT LEAST ONE COPOLYMER HAVING OLEFIN AND ACRYLIC ESTER MONOMER UNITS AS THE MAIN CONSTITUENTS, WHICH POSSESS IMPROVED PROPERTIES IN TACKINESS, PROCESSABILITY, OIL RESISTANCE, THERMAL RESISTANCE, WEATHERING RESISTANCE AND THE LIKE.

Patented Sept. 3, 1974 3,833,689 ELASTOMERIC COMPOSITIONS CONTAINING OLEFIN-ACRYLIC ESTER COPOLYMER Teruyoshi Usamoto, Higashi-osaka, Taisuke Okita, Toyonaka, Nobuyuki Yoshida, Takatsuki, Masaaki Hirooka, Ibaraki, Isoji Taniguchi, Toyonaka, and Shyozaburo Imai, Ibaraki, Japan, assignors to Sumitomo Chemical Co., Ltd., Osaka-shi, Japan No Drawing. Continuation of abandoned application Ser. No. 29,276, Apr. 16, 1970. This application Aug. 10, 1972, Ser. No. 279,289

Claims priority, application Japan, Apr. 16, 1969, 44/29,900; Mar. 5, 1970, 45/19,442 Int. Cl. C08f 37/18 US. Cl. 260-897 B 26 Claims ABSTRACT OF THE DISCLOSURE Elastomeric compositions comprising 1 part by weight of at least one curable elastomer and 0.01 to 100 parts by weight of at least one copolymer having olefin and acrylic ester monomer units as the main constituents, which possess improved properties in tackiness, processability, oil resistance, thermal resistance, weathering resistance and the like.

This is a continuation of application Ser. No. 29,276, filed Apr. 16, 1970, now abandoned.

The present invention relates to elastomeric compositions comprising olefin-acrylic ester copolymers and curable elastomers. This invention also relates to co-curable elastomeric compositions comprising curable olefin-acrylic ester copolymers and rubbers.

In the blending of polymers, there is very often observed insufiicient compatibility. Still, no favorable cocurability can be expected in the insufficient blending if the cured rubber is aimed. For instance, favorable results of curing are difficult to be attained by blending an elastomer having polar group for the purpose of improving the poor solvent resistance of hydrocarbon rubbers. There are some synthetic rubbers of which application is restrained because of inferiorities of properties such as tackiness and processability in the uncured state of the compound used. Therefore, it is frequently requested to incorporate a compound having a polar group to the synthetic rubber without loss of the inherent properties of the rubber, but prac tically such a suitable compound is difiicult to be found. As results of investigations on the method of admixing an ester compound with various elastomers, the present inventors have found that an olefin-acrylic ester copolymer is successfully compatible and blendable with a broad scope of elastomers and that the resultant compositions can be cured without accompanying deteriorations of properties of the cured products. Thus, the present invention has been established.

Accordingly, a basic object of the present invention is to provide an elastomeric composition containing a copolymer having olefin and acrylic ester monomer units as main constituents and at least one curable elastomer. Especially, the invention provides an elastomeric composition containing 0.01 to 100 parts by weight of olefin-acrylic ester copolymer on the basis of 1 part by weight of curable elastomer. A special object of the present invention is to provide a co-curable composition comprising a curable olefin-acrylic ester copolymer and at least one curable elastomer. A further object of the present invention is to provide a process for preparing an elastomeric composition containing olefin-acrylic ester copolymer and curable elastomer.

The olefin used in the copolymer of this invention is effective for increasing the affinity for hydrocarbon elastomers and thus the present copolymers are superior to the acrylic ester homopolymers. The polar ester group brings to the elastomer improvements of tackiness, oil resistance, chemical resistance, weathering resistance and aging resistance. It is one of the important effects on the present invention that there has been overcome the defects including poor tackiness and ill processability of the uncured elastomeric compound of which many conventional synthetic rubbers are suffered. Of synthetic rubbers, ethylenepropylene diene terpolymers and butadiene-styrene copolymers show particularly poor tackiness and ill processability in the uncured elastomeric compound, of which improvement is desired. The said defects can be now overcome by using the olefin-acrylic ester copolymers of this invention which are well compatible with those elastomers, and there is observed no deterioration on the properties of the cured products.

It is another advantage of the elastomeric compositions of this invention that the olefin-acrylic ester copolymer has an affinity for a large number of elastomers and is blendable with them successfully. The olefin-acrylic ester copolymers including unsaturated group are sulfur-curable, and the compositions including these copolymers are cocurable with the opponent elastomer whereby further enhanced improvements are attained.

It is one of the most important points in the present invention that the olefin-acrylic ester copolymers can be incorporated with a wide range of rubbers from low-unsaturated rubbers to diene rubbers having high unsaturation to give co-cured elastomers having sufficiently good mechanical strengths. Heretofore, it has been easy to cocure a low-unsaturated rubber and other low-unsaturated rubber or a diene rubber and other diene rubber, but it has been difficult to co-cure a low-unsaturated rubber with a diene rubber. For instance, EPDM rubber has not been obtained co-cured materials with diene rubbers having good properties, and there has been many problems. In such circumstances, the compositions of the present invention are of interest and important in the practical points of view.

As elastomers which can be combined with the olefinacrylic ester copolymers, there are exemplified sulfur-curable or amine-curable various synthetic elastomers and natural elastomers including ethylene-propylene rubber, butyl rubber, butadiene-styrene rubber, polybutadiene rubber, butadiene-acrylonitrile rubber, polyisoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, halogenated ethylene-propylene rubber and halogenated butyl rubber. Above all, hydrocarbon rubbers such as ethylenepropylene-diene rubber, butyl rubber or butadiene-styrene rubber are more favorable for combination with the olefinacrylic ester copolymers. The elastomeric component may be used in a mixture of one or more sorts of these rubbers.

Since the olefin-acrylic ester copolymer of this invention is combined with an elastomer to form an elastomeric composition, the olefin-acrylic ester copolymer having a low secondary transition point may be favorably used. Although an acrylic ester homopolymer shows poor compatibility with synthetic elastomers or natural rubber, the olefin component in the copolymer increases the affinity for hydrocarbon elastomers. From this meaning, there may be favorably used such olefins as form a polymer having a low secondary transition point. Such a favorable olefin involves an olefinic hydrocarbon and their halogenated compound containing 2 to 20 carbon atoms, more favorably a-olefin containing 3 to 8 carbon atoms. Diolefins and halogen-containing olefins and dienes which can be converted into elastomers readily may be used, too. In these cases, the copolymers of diolefins or halogenated olefins with acrylic esters are sulfur-curable or aminecurable. In these olefins, isobutylene and propylene are especially useful. Examples of the olefins, that is, are isobutylene, propylene, ethylene, butene-l, pentene-l, 2- methylbutene-l, 2-methylpentene-1, hexene-l, butene-2, 4-methylpentene-1, Z-methyl 4 phenylbutene-l, octadecene-l, 1,3-butadiene, 1,3-pentadiene, isoprene, 1,4-hexadiene, 1,3,5-hexatriene, chloroprene, ,6-methallyl chloride and 2-methyl-4-chloropentene-l.

For the ester group in the acrylic ester which is copolymerized with the olefin, hydrocarbon groups containing 1 to carbon atoms and their halogenated compounds are preferable. Example of the hydrocarbon group are alkyl, alkenyl, aryl, aralkyl, aralkenyl, alkylaryl, alkenylaryl, cycloalkyl and cycloalkenyl, and their halogenated groups. In particular, an alkyl group having 1 to 10 carbon atoms is suitable for elastomers, and an alkyl having 2 to 8 carbon atoms is more suitable. Examples of the acrylic ester are methyl acrylate, ethyl acrylate, propyl acrylate, allyl, acrylate, crotyl acrylate, n-butyl acrylate, t-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2- ethylhexyl acrylate, cyclo pentenyl, acrylate, octadecyl acrylate, methallyl acrylate, citronellyl acrylate, cinnamyl acrylate, o-tolyl acrylate, benzyl acrylate, cyclohexyl acrylate, norbornenylmethyl acrylate, Z-chloroethyl acrylatc, 3-chloropropyl acrylate, ,B-chloroallyl acrylate, methyl thiolacrylate and ethyl thiolacrylate. Still, there may be used acrylic esters having a substitutent such as a hydrocarbon group, a halohydrocarbon group or a halogen atom at the aor fi-position of the acrylic acid.

As sulfur-curable copolymers, there are favorably used such copolymers as olefin and/or acrylic ester containing directly at least partially a double bond to act as a sulfurcuring site. As unsaturated groups in the component to be sulfur-curing site, there may be favorably used components having an internal double bond inert to the polymerization because there is observed no formation of troublesome gels. Thus, it is favorable to use acrylic acid unsaturated esters above described illustratively as a sulfur-curing site.

Further, as co-monomer components atfording the sulfur-curing site, there may be effectively used a rather small amount of monomers producing a polymer having a higher secondary transition point. As such co-monomers, there are exemplified various polyene hydrocarbons or halohydrocarbons and acrylic acid unsaturated esters which are out of the scope of the olefin because of higher secondary transition point, and as the other co-monomers, unsaturated ethers and acrylic acid unsaturated amides. These .comonomers include divinylbenzene, p-isopropenylstyrene, p-allylstyrene, S-ethylidene-Z-norbornene, 5- methyl-Z,S-norbornadiene, dicyclopentadiene, 1,5-cyclooctadiene, 6-methyl-4,7,8,9-tetrahydroindene, 4-viny1- cyclohexene, aldrin, p-(l'-chloro-l-propenyl)styrene, 1'- propenyl vinyl ether, cyclohexenyl acrylate and (N-(1- propenyljtacrylamide.

The olefin-acrylic ester copolymers having halogen atom are in general amine-curable. For instance, halogencontaining acrylic esters and halogen containing olefins may be used at least partially for copolymerization. Further, other halogen-containing compounds which can be copolymerized with olefin and acrylic ester may be used as a third component for copolymerization. Favorable examples of the third component are halogen-containing unsaturated ethers including 2-chloroethyl vinyl ether, 4-chlorobutyl vinyl ether and isobutyl 2-chloroallyl ether, and halogenated olefins and halogen-containing carboxylic acid unsaturated esters may be also used, too. Still, there may be used other olefin-acrylic ester copolymers which are modified by using the other comonomers.

The olefin-acrylic ester copolymers in the elastomeric compositions of the present invention are prepared in an arbitrary method. In particular, copolymers having high molecular weight can be effectively prepared from olefin and acrylic ester via a complex of a Lewis acid such as metal halide with carbonyl groups of the ester. The copolymerization may proceed effectively in the presence of an organic metal compound as an initiator. The important copolymers are alternating ones which may be prepared elfectively by copolymerizing olefin and acrylic ester in the presence of an organic halide of aluminum or boron. Ethylenically unsaturated monomers having the other double bond or a halogen atom may be used in addition to the olefin and acrylic ester to give multicomponent alternating interpolymers. The details of such multicomponent alternating copolymers were described in the specification of French Pat. No. 1,528,220.

As the preferable olefin-acrylic ester copolymers of the present invention, there are copolymers derived from such olefins as isobutylene and propylene and acrylic esters having ester groups selected from ethyl, n-butyl, 2-ethylhexyl and methyl esters, as main constituents. The copolymer using ethyl acrylate is suitable as an elastomer, and the copolymers derived from esters having more than three carbon atoms (e.g. n-butyl ester, 2-ethylhexyl ester) are favorable for the improvement of tackiness. Compositions of the copolymer are desirable to be selected so that the products are elastomeric, and there is ordinarily used a copolymer comprising 10 to 70 mole percent, preferably 30 to 50 mole percent, of the olefin component and to 30 mole percent, preferably 70 to 50 mole percent, of the acrylic ester component. As a third component, other comonomers can be copolymerized in an extent enough not to damage the elastomeric properties. In general, 0.1 to 30 mole percent, preferably 0.5 to 10 mole percent, of the co-monomer having two unsaturated groups or a halogen atom may be incorporated into the copolymer for working as a sulfur-curing site or an amine-curing site. Still, much more functional groups can be incorporated, e.g. for the purpose of increasing the mutual afiinity with diene rubbers or for the other purposes.

The most important copolymers in the present invention are the so-called alternating copolymers wherein olefin and acrylic ester are combined alternately, i.e. 50 mole percent of olefin and 50 mole percent of acrylic ester are contained. In the multicomponent alternating coploymer wherein other co-monomers are incorporated as the third components, 50 mole percent of A group monomers and 50 mole percent of B group monomers are contained. Said co-monomers are classified in A group and B group whether they react similarly as olefin or as acrylic ester. The detailed descriptions thereof appears in Japanese Patent Applications Nos. 36,745/ 1966, 70,976/ 1968 and 99,858/ 1969. The A group monomers involve a-olefins, internal olefins, styrenes, other ethylenically unsaturated hydrocarbon monomers, dienes, carboxylic acid unsaturated esters, unsaturated ethers and halogen-substituted compounds thereof, and the B group monomers involve acrylonitrile, acrylic acid, acrylic esters, acryloyl halides, acrylamides, their halogenated compounds and acor fi-substituted compounds thereof.

The copolymers in the present invention have in general high molecular weights and the intrinsic viscosity measured at 30 C. in benzene solution is in the range of 0.1 to 10 dl./g., preferably 0.5 to 7 dl./ g.

The elastomeric compositions of the present invention comprise the olefin-acrylic ester copolymer and rubber in a free ratio. For instance, an elastomeric composition containing 0.01 to parts by weight of the olefinacrylic ester copolymer per 1 part by Weight of the rubber is practically valuable. When there are used noncurable olefin-acrylic ester copolymers, 1 to 40 parts by weight, favorably 2 to 20 parts by weight, of the copolymer per 100 parts by weight of the elastomer may be preferably used. The elastomeric compositions of this invention may be prepared by blending the whole components in a voluntary method, for instance, with a roll mill, a Banbury mixer, a calender roll, a kneader blender, or an extruder.

In the present invention, a co-curable elastomeric composition comprising a sulfur-curable olefin-acrylic ester copolymer and a sulfur-curable elastomer is very important. In this case, the proportion of blending may be arbitrarily chosen, and every composition is useful. In particular, favorable elastomeric compositions are such black, hard clay, fine-powdery silicic acid, artificial silicate and calcium carbonate; plasticizers such as process oil and resins; minerals such as zinc oxide, magnesia and titania; stearic acid and antioxidants.

elastomers as sulfur-curable ethylene-propylene co- Practical and presently-preferred embodiments of the polymer, butyl rubber and butadiene-styrene copolymer, 5 present invention are illustratively shown in the following and particularly elastomeric compositions including isoexamples wherein parts are by weight.

lgllllltylene-ethyl acrylate-acrylic unsaturated ester are use- EXAMPLE 1 It is well known that sulfur-curable ethylene-propylene AH Olefin-acrylic ester Copolymer 20 elastomer (EPDM) is hardly co-curable with diene elas 10 P was admixed with hyl -propylene-5-ethy1ic1enetomers such as butadiene-styrene rubber, polybutadiene 2-norb0rnene terpolymer (Royalene 501, manufactured and natural rubber. Thus, it is surprising that co-cured by Uniroyal C0., Ltd.) (100 parts) at 40 to 50 C. by elastomeric compositions having excellent mechanical rolls- T0 the resulting mixture, there e added properties in the cured state can be obtained by blending and blended HAF Carbon black P Zine Oxide a sulfur-curable isobutylene-acrylic ester copolymer and P stearlc field P sulfur P tetra EPDM in any proportion. methylthiuram monosulfide (1.5 parts) and Z-mercapto- On the other hand, an elastomeric composition combenZOthiaZOle (0- P prising an amine-curable elastomer and a halogen-con- The Obtained Compound was Passed through an p taining olefin-acrylic ester copolymer can be co-cured by lure of rolls to g a sheet (about 1 thickness), amine-curing, and halogen containing olefin-acrylic ester which was used as a test sample for measurement of copolymers may be also added to sulfur-curable elastaeklhess- The measurement was carried out using a t r fo improving properties th fl pick-up type tack meter (manufactured by Toyo Seiki The elastomeric compositions of this invention can be Co., L under the following conditions: temperature, combined with various other components such as curing loading weight, 500 loading Period, Seconds; agents, sulfur, fillers, stabilizers and diluents. 25 Peeling Tale, l0 CmJmlmlle- Sulfur and sulfur-curing accelerators may be used for The said sample Product was cured under Pressing at obtaining the sulfur-cured products from the curable 150 C. for 10 minu s and sllhieeted to measurement f elastomeric compositions of this invention. Such curing- P y Properties The modulus at 200% elongation, accelerators involve various compounds in thiazole series, tensile strength at break, elongation at break and h sulfenamide series, thiazoline series, thiuram series, di- 11ess were measured at C. n a t nsil rate of 500 thiocarbamate series, aldehyde-amine series and guanidine him/minute with a tensile tester (manufactured y series. Examples of the curing accelerators are 2-mer- Shimadlu Selsakusho according to the HS-K*630l captobenzothiazole, dibenzothiazyl disulfide, methylenemethodaniline mercaptobenzothiazole, cyclohexylbenzothiazyl- The used olefin-acrylic eslel' copolymers are shown sulfenamide, Z-mercaptothiazoline, tetramethylthiuram di- 111 Table 1, and Table 2 shows the tacklhess and P y sulfide, tetramethylthiuram monosulfide, tellurium di- Properties of the somposltlohs Comprising Olefin-acrylic rnethyldithiocarbamate, zinc dimethyldithiocarbamate, ester copolymers and y -P py y zinc dibenzyldithiocarbamate, zinc dibutyldithiocarbal-norbornene terpolymermate, dinitrophenyl dimethyldithiocarbamate, butylalde- 40 TABLE 1 hyde-aniline condensate, and di-o-tolylguanidine. These Ratio of compounds may be used alone or in a mixture of more Sample monomeric than one compound. A suitable curing-accelerator may number P 11 be selected according to the sort of elastomers, and there Propylene-ethylacrylate W 4.25 is used ordinarily 0.1 to 5 parts by weight, favorably 0.5 15 figmggmgfiggggggfi 28423 if; to lpartfs tiy wrlarght, of tljrke accelaelrator per 10? palrts by p vn figggzgggg-lzouglyitgrgaite i welg t o t e e astomer. suita e amount 0 so fur is e 0.1 to 5 parts by weight, favorably 0.5 to 2 parts by Pentene'butylacrylate 50/50 weight, per 100 parts by weight of elastomer. Measured at benzene- TABLE 2 Control Embodiments of the invention gthyiene-propyleneeethylidene-2-norbornene terpolymer (parts).-- 100 100 100 100 100 100 100 100 100 100 100 100 100 s oll ffln r r 11 II III III IV IV v V v1 v1 amount (parts) 10 20 10 20 10 20 10 20 10 20 10 20 Tack}ness(g./mn 1.) 24.5 39.2 51.5 35.6 49.3 44.5 57.9 44.3 54.3 37.8 50.0 39.0 49.3 Physical properties:

200% modulus (kg/0111. 90 86 84: 82 81 80 79 83 81 86 78 84 75 Tensile strength (kgJcmJ)- Elongation (percent)- 425 505 535 490 515 485 550 450 495 435 485 420 435 1 Numerals correspond to those in Table 1.

Amine-curable compositions may be cured with a basic 6 EXAMPLE 2 substanfze as a .lmlne'curmg i The amme'cu.nng Copolymer I, III or V as shown in Table 1 (10 or 20 agents involve basic compounds having at least two nitrot d t b t bb SB gen atoms such as aliphatic polyamines, heterocyclic par S) was me W1 8 yrenelane m at R compounds having at least two nitrogen atoms their 1,500, manufactured by Japan Synthetic Rubber Co., Ltd.) amine condensates Such as was thioureas Sch b (1 00 parts) at 40 to 50 C. by two rolls. To the resulting 5 r 1 ases mixture, there were added and blended HAF carbon black or carbamates. The amine-curing may be favorably ef- (50 parts) Zinc Oxide (5 parts), Stearic acid (1 part), fected the Presence of sulfur sulfur -(2 parts) and N-cyclohexyl-Z-benzothiazylsulfen- Other spontaneous components may be added to the id t elastomeric compositions of the present invention, if de- The tackiness and physical properties of the obtained sired. These components involve fillers such as carbon compound were measured as in Example 1.

The results are shown in Table 3.

TABLE 3 Control Embodiments of the invention Styrene-butadlene Crublber (parts) 100 100 100 100 100 100 100 o i't I I III III V V Amount (parts) 10 20 10 20 Tackiness (g./mm.) 28.0 41.5 59.3 43.2 61.1 45.5 69.8 Physical properties:

modulus (kg. 111. 41 39 37 37 31 40 35 Tensile strength kg. In. 233 221 215 219 205 227 213 Elongation (percent) 700 785 805 795 850 755 800 1 Numerals correspond to those in Table 1.

EXAMPLE 3 Fifteen parts of isobutylene-n-butyl acrylate-Z-chloroethyl vinyl ether terpolymer (chlorine content, 2.53%; isobutylene, 49 mol percent) (polymer A) or propylene- 2-ethylhexyl acrylate-Z-chloroethyl acrylate terpolymer (chlorine content, 1.67%; propylene, 47 mol percent) (polymer B) were blended with ethylene-propylene-S- ethylidene-Z-norbornene terpolymer (Royalene 501) (100 parts) by two rolls. To the resulting mixture, there were added and blended HA F carbon black '(50 parts), zinc oxide (5 parts), stearic acid (1 part), sulfur (1.5 parts), tetrame'thylthiuram disulfide (1.5 parts) and Z-mercaptobenzothiazole (0.5 part).

The obtained compound was passed through an aperture of rolls to give a sheet 1 mm. thickness), which was used as a test sample for measurement of taekiness. The measurement was carried out at C. with a pick-up type tack meter (manufactured by Toyo Seiki Co., Ltd).

The results are shown as follows:

Composition of compound: Tackiness (g./mm.) Ethylene-propylene-5-ethylidene-2 norborneneterpolymer alone (control) 25.1 lPolymer A blended 60.3 Polymer -B blended 55.7

' EXAMPLE 4 Fifteen parts of isobutylene-n-butyl acrylate-Z-chloroethyl vinyl ether terpolymer (polymer A) or propylene-2- ethylhexyl acrylate 2 chloroethyl acrylate terpolymer (polymer -B) were blended with butadiene-styrene c0- polymer (100 parts) (SBR 1500, manufactured by Japan Synthetic Rubber Co., Ltd.) by two rolls. To the resulting mixture, there were added and blended HAP carbon black (50 parts), zinc oxide (5 parts), stearic acid (1 part), sulfur (2 parts) and N-cyclohexyl-2-benzothiazylsulfenamide (2 parts). The tackiness of the resultant compound was measured as in Example 3.

The results are shown as follows:

Composition of compound: Tackiness (g./-rnm.) Butadiene-styrene copolymer alone (control) 30.6

Polymer A blended 58.6 Polymer B blended 55.2

EXAMPLE 5 Ethylene-propylene-dicyclopentadiene terpolymer (propylene content, 26 mol percent; iodine value, 10.2; intrinsic viscosity measured at 70 C. in xylene, 1.60 dl./g.; Mooney viscosity, ML 52) (25 parts), isobutylene-ethyl acrylate-allyl acrylate terpolymer (iodine value, 6.2; isobutylene, 48 mol percent) (75 parts), HAP carbon black (50 parts), zinc oxide (5 parts), tetramethylthiuram disulfide (1.5 parts), mercaptobenzothiazole (0.5 parts), sulfur (1.5 parts) and stearic acid (1 part) were blended by a plastograph. The resultant compound was cured under pressing at 160 C. for 40 minutes. On the tensile test, the following results were obtained: tensile strength at break, 150 kg./cm. elongation at break, 310%. The cured product of the isobutylene-ethyl acrylate-allyl acrylate terpolymer alone gave the following results: tensile strength at break, 123 kg./cm. elongation at break,

180%. The above results indicate that the blended composition is well co-cured.

EXAMPLE 6 Ethylene-propylene-dicyclopentadiene terpolymer (propylene content, 25 mol percent; iodine value, 10.2; intrinsic viscosity measured at 70 C. in xylene, 1.60 dl./ g.) (75 parts), isobutylene-ethyl acrylate-crotyl acrylate terpolymer (iodine value, 7.3; isobutylene, 49 mol percent) (25 parts), FEF carbon black (50 parts), zinc oxide (5 parts), stearic acid (1 part), tetrarnethylthiuram monosulfide (1.5 parts), mercaptobenzothiazole (05 part) and sulfur (1.5 parts) were blended by a plastograph. The resultant compound was cured under pressing at 160 C. for 40 minutes to give an elastomeric product having the following physical properties: tensile strength at break 205 kg./cm. elongation at break, 440%; 300% modulus, kg./cm. The cured product was dipped in ASTM No. 1 oil at C. for 70 hours whereby the weight increase was 117.3%. The cured product of the ethylene-propylene dicyclopentadiene terpolymer alone showed 212.5% in weight increase.

These results mean that the co-cured composition holds enhanced oil resistance.

EXAMPLE 7 lsobutylene-allyl acrylate-ethyl acrylate terpolymer (isobutylene, 49 mol percent; allyl acrylate, 2.7 mol percent; ethyl acrylate, 48.3 mol percent (50 parts), butadiene-styrene copolymer (ISR-1500, manufactured by Japan Synthetic Rubber Co., Ltd.) (50 parts), zinc oxide (3 parts), FEF carbon black (40 parts), stearic acid (2 parts), sulfur (1.5 parts) and N-cyclohexyl-Z-benzothiazylsulfenamide (2 parts) were blended by two rolls. The resultant compound was cured under pressing at 150 C. for 40 minutes to give a co-cured elastomer being 141 kg/cm? in tensile strength at break and 240% in elongation at break.

EXAMPLE 8 Isobutylene-allyl acrylate-ethyl acrylate terpolymer (isobutylene, 49 mol percent; allyl acrylate, 2.7 mol percent; ethyl acrylate, 48.4 mol percent) (50 parts), butyl rubber (50 parts), zinc oxide (5 parts), HAF carbon black (50 parts), stearic acid (1 part), sulfur (1.5 parts), tetramethylthiuram disulfide (1.5 parts) and mercaptobenzothiazole (0.5 part) were blended by two rolls. The resultant compound was cured under pressing at C. for 40 minutes to give a co-eured elastomer being 158 kg./cm. in tensile strength at break and 480% in elongation at break.

EXAMPLE 9 Isobutylene-allylacrylate acrylate-ethyl acrylate terpolymer (isobutylene, 49 mol percent; allyl acrylate, 2.7 mol percent; ethyl acrylate, 48.4 mol percent) (50 parts), butadiene-acrylonitrile copolymer (Hycar-lOOO x 132) (50 parts), zinc oxide (5 parts), SRF carbon black (50 parts), sulfur 1.5 parts), stearic acid (1 part) and diben'zothiazole disulfide (1 part) were blended by two rolls. The resultant compound was cured under pressing at 150 C. for 40 minutes to give a co-cured elastomer being 128 kg./cm. in tensile strength at break and 200% in elongation at break.

What is claimed is:

1. An elastomeric composition comprising one part by weight of a curable ethylene-propylene rubber and 0.01 to 100 parts by weight of at least one copolymer having aliphatic a-olefin units of 3 to 20 carbon atoms and alkyl acrylate units with alkyl groups of 1 to 20 carbon atoms as the main constituents, said copolymer comprising 10 to 70 mole percent of the olefin monomer units and 90 to 30 mole percent of the acrylic ester monomer units.

2. An elastomeric composition according to claim 1, wherein the olefin monomer unit in the copolymer is isobutylene or propylene.

3. An elastomeric composition according to claim 1, wherein the acrylic ester monomer unit in the copolymer is ethyl acrylate, n-butyl acrylate, Z-ethylhexyl acrylate or methyl acrylate.

4. An elastomeric composition according to claim 1, wherein the copolymer has alternating monomer sequences.

5. An elastomeric composition according to claim 1, wherein sulfur and a sulfur-curing agents are contained.

6. An elastomeric composition according to claim 1, wherein the ethylene-propylene rubber comprises an ethylene-propylene--ethylidene 2 norborneneterpolymet, and the copolymer comprises a propylene-ethyl acrylate copolymer.

7. An elastomeric composition comprising one part by weight of at least one curable elastomeric ethylenepropylene rubber and 0.01 to 100 parts by Weight of at least one copolymer having olefin and acrylic ester monomer units, said olefin units having 3 to 8 carbon atoms, and said copolymer being composed of to 70 mole percent of the olefin monomer units and 90 to 30 mole percent of the acrylic ester monomer units.

8. An elastomeric composition according to claim 7, wherein the olefin monomer unit in the copolymer is isobutylene or propylene and the acrylic ester monomer unit in the copolymer is ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate or methyl acrylate.

9. An elastomeric composition according to claim 7, wherein the curable elastomer is ethylene-propylene rubher and wherein the copolymer has an alternating sequence of olefin and acrylic ester monomer units.

10. An elastomeric composition according to claim 7, wherein the copolymer has an intrinsic viscosity of 0.1 to 10 d1./ g. as measured in benzene at 30 C.

11. An elastomeric composition according to claim 7, wherein the acrylic ester units have from 1 to 20 carbon atoms.

12. An elastomeric composition according to claim 11, wherein said composition contains from 1 to 40 parts by weight of the copolymer per 100 parts by weight of the elastomer.

13. The elastomeric composition according to claim 11, wherein said composition contains from 2 to 20 parts by weight of the copolymer per 100 parts by weight of the elastomer.

14. An elastomeric composition according to claim 1, wherein said composition contains from 1 to 40 parts by weight of the copolymer per 100 parts by weight of the elastomer.

15. An elastomeric composition according to claim 1, wherein said composition contains from 2 to 20 parts by weight of the copolymer per 100 parts by weight of the elastomer.

16. An elastomeric composition according to claim 1, wherein said u-olefin units have 3 to 8 carbon atoms.

17. An elastomeric composition according to claim 1, wherein said a-olefin unit is selected from the group consisting of isobutylene, propylene, butene-l, pentene-l, Z-methyIbutene-l, 2-methylpentene-1, hexene-l, butene-Z, 4-methylpentene-1, octadecene-l.

'18. An elastomeric composition according to claim 1, wherein the alkyl groups on the alkyl acrylate unit are halogenated.

10. An elastomeric composition according to claim 1, wherein said alkyl acrylate is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, allyl acrylate, crotyl acrylate, n-butyl acrylate, t-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, Z-ethylhexyl acrylate, cyclopentenyl acrylate, octadecyl acrylate, methallyl acrylate, citronellyl acrylate, cinnamyl acrylate, o-tolyl acrylate, benzyl acrylate, cyclohexyl acrylate, norbornenylmethyl acrylate, 2-chloroethyl acrylate, 3-chl0ropropyl acrylate, p-chloroallyl acrylate, methyl thiolacrylate and ethyl thiolacrylate.

20. An elastomeric composition according to claim 1, wherein the alkyl acrylate unit in said copolymer is an acrylic acid unsaturated ester.

21. An elastomeric composition according to claim 1, wherein the olefin acrylate copolymer additionally contains a polymerized monomer selected from the group consisting of diene monomers, halogen-containing unsaturated ester monomers and halogen containing unsaturated ether monomers.

22. An elastomeric composition according to claim 1, wherein said copolymer additionally contains a polymerized monomer selected from the group consisting of divinylbenzene, p isopropenylstyrene, p allylstyrene, 5-ethylidene-2-norbornene, 5 methyl-2,S-norbornadiene, dicyclopentadiene, 1,5 cyclooctadiene, 6-methyl-4,7,8,9- tetrahydroindene, 4-vinylcyclohexene, aldrin, p-(1'-chloro-1-propenyl)-styrene, 1-propenyl vinyl ether, cycle hexenyl acrylate and N-(l'-propenyl) acrylamide.

23. An elastomeric composition according to claim 1, wherein said copolymer additionally includes a polymerized monomer selected from the group consisting of 2-chloroethyl vinyl ether, 4-chlorobutyl vinyl ether and isobutyl 2-chlor0allyl ether.

24. An elastomeric composition comprising 1 part by weight of a curable halogenated ethylene-propylene rubber and 0.01 to 100 parts by weight of at least one co polymer having aliphatic a-olefin units of 3 to 20 carbon atoms and alkyl acrylate units with alkyl groups of 1 to 20 carbon atoms as the main constituents, said copolymer comprising 10 to mole percent of the olefin monomer units and to 30 mole percent of the acrylic ester monomer units.

25. An elastomeric composition according to claim 1, wherein said ethylene-propylene rubber is EPDM.

26. An elastomeric composition which comprises one part by weight of at least one ethylene-propylene rubber and 0.01 to parts by weight of at least one copolymer having olefin units and acrylic ester monomer units, said copolymer being composed of 10 to 70 mole percent of olefin monomerunits having 3 to 20 carbon atoms, 90 to 30 mole percent of acrylic monomer ester units, and 0.1 to 30 mole percent of a monomer unit selected from the group consisting of a monomer having at least one double bond and a monomer having at least one halogen atom.

References Cited UNITED STATES PATENTS 3,326,833 6/1967 Raley 26028.5

MURRAY TILLMAN, Primary Examiner C. I. SECOURO, Assistant Examiner U.S. Cl. X.R. 

